<!DOCTYPE html>
<html lang="zh-CN">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>包装类</title>
    <script type="text/javascript">
        var num = new Number(3);
        var str = new String("hello");
        var bool = new Boolean(true);

        num.hello = "asdf";

        console.log(num.hello);

    </script>

</head>

<body>

</body>

</html>